You all have a currupt timeline.
This problem should simply NOT be happening, but it does, maybe its a Feature.
Go to File menu, make a new sequence (do not make a dup of existing timeline).
Double click the new timeline, so its loaded on the screen.
Go to the working timeline you are cutting with, select all, copy, paste into new timeline.
This issue has bugged be for the life of 4.5 it drives me crazy!!!
Yet, I may be wrong…
Chirs